diff --git a/src/Assigning/Assignment.hs b/src/Assigning/Assignment.hs
index 8c845f922..676b9af40 100644
--- a/src/Assigning/Assignment.hs
+++ b/src/Assigning/Assignment.hs
@@ -147,8 +147,10 @@ location = tracing Location `Then` return
 getRubyLocals :: HasCallStack => Assignment ast grammar [ByteString]
 getRubyLocals = tracing GetRubyLocals `Then` return
 
-putRubyLocals :: HasCallStack => [ByteString] -> Assignment ast grammar ()
-putRubyLocals l = tracing (PutRubyLocals l) `Then` return
+putRubyLocals :: (HasCallStack, Enum grammar, Eq1 ast, Ix grammar) => [ByteString] -> Assignment ast grammar ()
+putRubyLocals l = mk (PutRubyLocals l) <|> mk End
+  where
+    mk a = tracing a `Then` return
 
 -- | Zero-width production of the current node.
 currentNode :: HasCallStack => Assignment ast grammar (TermF ast (Node grammar) ())
diff --git a/src/Language/Ruby/Assignment.hs b/src/Language/Ruby/Assignment.hs
index 0203cb119..729616a4e 100644
--- a/src/Language/Ruby/Assignment.hs
+++ b/src/Language/Ruby/Assignment.hs
@@ -147,14 +147,14 @@ expressions = makeTerm'' <$> location <*> many expression
 parenthesizedExpressions :: Assignment
 parenthesizedExpressions = makeTerm'' <$> symbol ParenthesizedStatements <*> children (Syntax.Paren <$> expressions)
 
-withExtendedScope :: Assignment.Assignment ast grammar a -> Assignment.Assignment ast grammar a
+withExtendedScope :: (Enum grammar, Ix grammar, Eq1 ast) => Assignment.Assignment ast grammar a -> Assignment.Assignment ast grammar a
 withExtendedScope inner = do
   locals <- getRubyLocals
   result <- inner
   putRubyLocals locals
   pure result
 
-withNewScope :: Assignment.Assignment ast grammar a -> Assignment.Assignment ast grammar a
+withNewScope :: (Enum grammar, Ix grammar, Eq1 ast) => Assignment.Assignment ast grammar a -> Assignment.Assignment ast grammar a
 withNewScope inner = withExtendedScope $ do
   putRubyLocals []
   inner